Synchronizing system.



B. P. ROWE.

SYNCHRONIZING SYSTEM.

APPLICATION FILED JUNE 24.1913.

1, 1 38 ,689. Patented May 11, 1915.

WITNESSES:

ATTORNEY UNITED STES OFI BERTRAND P. ROWE, F WILKINSBURG, PENNSYLVANIA,ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, ACORPORATION OF PENNSYLVANIA.

SYNCHRONIZING SYSTEM.

Specification of Letters latent.

Patented May 11, 1915.

Application filed. June 24, 1913. Serial No. 775,503.

To all whom it may concern:

Be it known that I, BERTRAND P. ROWE, a citizen of the United States,and a resident of Wilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement inSynchronizing Systems, of which the following is aspecification.

My invention relates to synchronous alternating current electricalmachines and it has special reference to means for controlling theoperation of such machines when connected in parallel.

The object of'myl invention is to provide a control system that shall besimple in arrangement and that shall obviate the possibility ofconnecting a synchronous machine for parallel operation with othermachines until the proper electrical conditions for synchronizing areattained. a

In electrical power generating stations, a number of generators areusually available for supplying power to the same bus-bars from whichthe load circuits receive their 2 energy. During the demands for powerof relatively small amounts, only a few machines are connected to thebus bars. As the load upon the station. increases, additional generatorsare connected to the bus bars to v supply the increasing demands forpower.

Before a synchronous generator can be successfully connected to the busbars for parallel operation with other such machines. proper electrical.conditions for synchroniz- 3 ing must be obtained upon the incomingmachine. A failure to secure these conditions will result in thedevelopment of abnormal electrical disturbances in the related circuitswhich may cause either the destruction of apparatus, or, in the event ofprotective de-- vices being inserted in the disturbed circuits, aninterruption of service. Because it is of the first importance tomaintain service at all times, it is highly desirable to insure againstthe interruption of such service by connecting an unsynchronizedgenerator to the bus bars.

'My invention automatically prevents the connecting of a generator tobus bars which are being supplied from other sources of power unless thesaid generator is in such condition as to cause no abnormal electricaldisturbances in the circuit when the connection to the bus bars isefiected.

' The single figure of the accompanying chronizing and subsequentlystant.

drawing is a diagrammatic view of a system 111 which synchronousgenerators are arranged for supplying energy to bus bars which, in turn,supply energy to load circuits.

The connections for determining when the generators are properlysynchronized and for connecting them to the bus bars when the properconditions for synchronizing obtain, are made in accordance withmy invention.

My invention may be applied to any number of synchronous generatorswhich are connected to the aforesaid group of bus bars and which requireprotection when synconnecting them to the said bus bars.

Referring .to the drawing, synchronous generators l and 2 are arrangedfor supplying three-phase currents to bus bars 3, 4 and 5. The generator1 is shown connected to the said bus bars. It is proposed to synchronizethe generator 2 with. the bus bars and, when the proper electricalconditions obtain, to connect the generator 2 so as to operate inparallel with the generator 1. I have assumed that the generator 2 hasbeen previously phased out that is, when the voltage of a pair of leads,such as 6 and 7 of generator 2, is in phase with the voltage of thecorresponding pair of bus bars 3 and t, all the voltages of the pairs ofgenerator leads, namely, 6, 7 and 8, are in phase with the voltages ofthe corresponding pairs of bus bars, namely, 3, 4 and 5.

In order to synchronize the generator 2 with the bus bars 3, 4 and 5, itis essential that the electromotive forces of the incoming generator 2and of the said bus bars shall be approximately equal at every in- Thisrequires that the current frequencies be the same; that the voltages, asmeasured by a voltmeter, be equal, and that the voltages be in phase. Itis necessary that these conditions obtain in each phase. If notfulfilled, an interchange of large-capacity currents between thegenerator 2 and the bus bars may lead to disastrous results and to theinterruption of service, unless means in the system, such as anembodiment of my invention, is provided which obviates the possibilityof connecting the generator 2 to the bus bars unless theabove-mentioned" synchronizing conditions have been attained. In orderto efiect the adjustments of speed and Voltages of the generator 2 forsynchronizing the same with the bus bars 3, and 5, 1 provide a Voltagetransformer 9, the primary windin 10 of which is connected to conductors6 and 7 of the said generator, and a Voltage transformer 11, the primarywinding 12 of which is connected to the bus bars 3 and i correspondingto the said gen erator conductors. ondary winding 13 of the transformer9 is connected, by means of conductors 14:, 15 and 16, to acorresponding terminal of. the secondary winding 17 of the transformer11. When a plug 18 of the synchronizing switch 19 engages a receptacle20, substantially as shown, the other terminals of the secondarywindings 13 and-17 er the transformers 9 and 11, respectively, areconnected in a circuit, which permits current to flow from the secondarywinding 13, alonga conductor 21, over an auxiliary switch 22, through anincandescent lamp 23, along a branch conductor 2 1 and a conductor 25,through an incandescent lamp 26, along conductors 27 and 28 to a branchconductor 29, through an auxiliary switch 30 of the synchronizing switch19, to a hranch conductor 31, and from thence to a conductor 32 whichcompletes the circuit through the secondary winding 17 of thetransformer 11. The lamps 23 and 26 are thus connected electrically inseries between corresponding terminals of the secondary transformerwindings 13 and 17. While synchronizing, m the electroinoti e forces ofthe windings 13 and 17 change from the condition of phase coincident tothat of phase opposition, the flow or" current through the lamps willvary from a minimum to a maximum value.

When the electromotiye forces induced in the windings 13 and 17 areexactly equal and opposite in phase, the current through. the lamps iszero. When the lamps burn at a maximum brilliancy, the voltages inducedin the secondary windings are in exact opposition. The rate of thepulsation from comple e darkness to maximum brilliancy of lamps dependsupon the relative current trequencies of the incoming generator 2 andthe bus bars 3, 4 and 5. adjusting the speed and the voltage of thegenerator .2,

this pulsation can he generally reduced to One terminal or: thesecperiod of the lamps, which the voltages are substantially in phase.Because of these uncertainties, 1 provide my system with synchroscope 33so arranged that it may he used with any number of synchronousgenerators, such as generators 1 and 2, which are to be connected to busbars 3, a and 5 for parallel operation.

When the synchronizing switch 19 is closed, the synchroscope 33, whichmay be of any standard type, is connected to the transformer windings 13and 17 substantially as described below. Current flows from the winding13, along conductors 21 and 3 1, over an auxiliary switch 35, alongconductors36 and37, to a binding post 38 of the synchroscope 33',through .a stationary coil (not shown) in said synchroscope, to abinding post 39, along conductors 10, 41 and 15, to the said winding 13.The trans former winding 17 supplies current which flows alongconductors 32 and 31, over the auxiliary switch 30, along conductors 29and 28, to a binding post 42, through a coil (not shown) of: thesynchroscope 33, to a binding post 43, along conductors a l, 41 and 16to the transformer windingv 17. By means of an indicator 15 rotatingover a dial upon the synchrosccpe, the operator can determine whetherthe incoming generator 2 is running too fast or too slow, what thedifierence is'in the speed oi? the said incoming generator and that ofthe generator 1, and the exact instant when the two said generators arein synchronism.

In order to eliminate the fallible judgment of the operator as to theproper instant for throwing the generator 2 upon the bus bars 3, 1 and5, TL have provided, in my system, means which automatically preventsthe connecting of the said generator to the bus bars when impropersynchronizing conditions exist which would cause abnormal anddestructive electrical disthrbances in the circuit if said connectionwere made.

The generator 2 may be thrown upon the bushars 3, t and5 at the properinstant by closing an oil switch 13 which connects generator leads 6, 7and 8, respectively, to bus bar leads 1-. -1-3 and 4:9. inserted in eachof said bus har leads is a primaryv winding of a current transformer 51,secondary windings 52 of which are connected in Y. @verload relays 53,coils 5 1- of which are shownconnected in open delta to the transformersecondary windings 52, are provided with magnetizable plungers 55.Mounted upon each of the saidplungers is a member 56 which is adapted tobridge a gap 57 extending between electrical contacts 58, when saidplunger is attracted'by the magnetizing coil 54. Thus, the members 56close electrical circuit which receives its excitation from bus bars 59and 69, here shown as befurnished with direct current energy suppliedfrom an exciter 61. Current will flow from the bus bar '59, alongconductor 62 and a branch conductor 63, over an auxiliary switch 64 ofthe synchronizing switch 19, along conductor 65, through the winding ofa trip coil 66 which is mounted upon the oil switch 46, along aconductor 67, con tact points 58, bridging members 56, conductors 68 and69, back to the bus bar 60 of the generator 61.

When the operator attempts to close the oil switch 46, and therebythrows the generator 2 upon the bus bars 3, 4 and 5 with which thegenerator has previously not been properly synchronized, the instantthat electrical connection is made between the generator leads 6, 7 and8 and the respective bus bar leads 47, 48 and 49 by means of members 70of the oil switch, an abnormal flow of current passes through theprimary windings 50 of the current transformer 51. The consequentabnormal currents being induced in the secondary windings 52 of saidtransformers cause. the plungers 55 of the overload relays 53' to becomeoperative, thereby closing the circuit through the exciting winding ofthe trip coil 66. As a plunger 71 of the said trip coil is drawnupwardly, it engages an arm of a pivoted lever 72, the other arm ofwhich is provided with a toothedportion 73. As the lever 72 is struck ablow by the plunger 71, the portion 73 is released from engagement withits cooperative and recessed portions 74 and 75 formed upon a liftinghandle 76 and a switch handle 77, respectively. A member 78, upon whichthe contact-making members 70 of the oil switch are mounted, thendisconnects the enerator leads from the bus bar leads. T e operator mayretain his hold upon the lifting handle 76, but the switch handle 77,having been released therefrom, willprotect the generator 2 and the busbar circuit from the abnormal electrical disturbances which would resultfrom con.- necting the said generator to said bus bar circuit whenimproper conditions for synchronizing exist. The, oil switch 46 willtake a position substantially similar to that shown by the switchassociated with the generator 2.

It is evident from the foregoing description that the oil switches 46may be released automatically to disconnect. their associated generatorsfrom the bus bars only when the synchrbnizing plug 18 is inserted in thereceptacle 20. After the generator 2 has been successfully connected tooperate in parallel with the bus bars,-the plug 18 is removed, whichobviates the possibility of automatically opening the oil switch 46because of the overloads demanding excess power from the said generator.

While I 1...... herein described in detail one embodiment of myinvention, it is not intended that my invention be limited to the,

specific arrangement and circuit connections disclosed, and I desirethat all variations in systems which do not depart from the spirit of myinvention, shall be included within its .vided with overload relays toactuate said auxiliary switches in the main control circuit.

2. The combination with a power circuit, an alternating currentdynamo-electric machine, a main switch adapted to connect the machine tosaid circuit, and electro-responsive means to prevent the permanentclosingof the main switch when the current flow from saiddynamo-electric machine exceeds a certain amount, of a main controlcircuit comprising an overload relay and said electro-responsive means,a synchronizing circuit, a multi-polar switch adapted to closesimultaneously the main control and the synchronizing circuits, and anauxiliary control circuit to actuate said overload relay, said auxiliarycontrol circuit comprising current transformers connected to the mainsof said dynamo-electric machine.

3. The combination with a power circuit, an alternating currentdynamo-electric machine, a main switch adapted to connect said machineto the power circuit, and electroresponsive means to prevent thepermanent closing of'the main switch, of a main controlv circuit forsaid electro-responsive means comprising an overload relay, asynchroniz-" ing circuit, a multi-polar switch to close said maincontrol circuit during the time onlythatthe synchronizing circuit isclosed, and

an auxiliary control circuit to actuate said overload relay when thecurrent flow from said dynamo-electric machine exceeds a certain amount.

In testimony whereof, I hate hereunto subscribed my name this 17th dayof June,

A BERTRAND P. ROWE. Witnesses:

' B. B. HINEs,

M. C. Mum.

